Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932688AbWEXLXE (ORCPT ); Wed, 24 May 2006 07:23:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932707AbWEXLTn (ORCPT ); Wed, 24 May 2006 07:19:43 -0400 Received: from smtp.ustc.edu.cn ([202.38.64.16]:12930 "HELO ustc.edu.cn") by vger.kernel.org with SMTP id S932711AbWEXLTM (ORCPT ); Wed, 24 May 2006 07:19:12 -0400 Message-ID: <348469549.18212@ustc.edu.cn> X-EYOUMAIL-SMTPAUTH: wfg@mail.ustc.edu.cn Message-Id: <20060524111910.544274094@localhost.localdomain> References: <20060524111246.420010595@localhost.localdomain> Date: Wed, 24 May 2006 19:13:13 +0800 From: Wu Fengguang To: Andrew Morton Cc: linux-kernel@vger.kernel.org, Wu Fengguang , Bart Samwel Subject: [PATCH 27/33] readahead: laptop mode Content-Disposition: inline; filename=readahead-laptop-mode.patch Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3397 Lines: 106 When the laptop drive is spinned down, defer look-ahead to spin up time. The implementation employs a poll based method, for performance is not a concern in this code path. The poll interval is 64KB, which should be small enough for movies/musics. The user space application is responsible for proper caching to hide the spin-up-and-read delay. ------------------------------------------------------------------------ For crazy laptop users who prefer aggressive read-ahead, here is the way: # echo 1000 > /proc/sys/vm/readahead_ratio # blockdev --setra 524280 /dev/hda # this is the max possible value Notes: - It is still an untested feature. - It is safer to use blockdev+fadvise to increase ra-max for a single file, which needs patching your movie player. - Be sure to restore them to sane values in normal operations! Signed-off-by: Wu Fengguang --- include/linux/writeback.h | 6 ++++++ mm/page-writeback.c | 2 +- mm/readahead.c | 30 ++++++++++++++++++++++++++++++ 3 files changed, 37 insertions(+), 1 deletion(-) --- linux-2.6.17-rc4-mm3.orig/include/linux/writeback.h +++ linux-2.6.17-rc4-mm3/include/linux/writeback.h @@ -86,6 +86,12 @@ void laptop_io_completion(void); void laptop_sync_completion(void); void throttle_vm_writeout(void); +extern struct timer_list laptop_mode_wb_timer; +static inline int laptop_spinned_down(void) +{ + return !timer_pending(&laptop_mode_wb_timer); +} + /* These are exported to sysctl. */ extern int dirty_background_ratio; extern int vm_dirty_ratio; --- linux-2.6.17-rc4-mm3.orig/mm/page-writeback.c +++ linux-2.6.17-rc4-mm3/mm/page-writeback.c @@ -389,7 +389,7 @@ static void wb_timer_fn(unsigned long un static void laptop_timer_fn(unsigned long unused); static DEFINE_TIMER(wb_timer, wb_timer_fn, 0, 0); -static DEFINE_TIMER(laptop_mode_wb_timer, laptop_timer_fn, 0, 0); +DEFINE_TIMER(laptop_mode_wb_timer, laptop_timer_fn, 0, 0); /* * Periodic writeback of "old" data. --- linux-2.6.17-rc4-mm3.orig/mm/readahead.c +++ linux-2.6.17-rc4-mm3/mm/readahead.c @@ -817,6 +817,31 @@ out: } /* + * Set a new look-ahead mark at @new_index. + * Return 0 if the new mark is successfully set. + */ +static inline int renew_lookahead(struct address_space *mapping, + struct file_ra_state *ra, + pgoff_t index, pgoff_t new_index) +{ + struct page *page; + + if (index == ra->lookahead_index && + new_index >= ra->readahead_index) + return 1; + + page = find_page(mapping, new_index); + if (!page) + return 1; + + __SetPageReadahead(page); + if (ra->lookahead_index == index) + ra->lookahead_index = new_index; + + return 0; +} + +/* * Update `backing_dev_info.ra_thrash_bytes' to be a _biased_ average of * read-ahead sizes. Which makes it an a-bit-risky(*) estimation of the * _minimal_ read-ahead thrashing threshold on the device. @@ -1760,6 +1785,11 @@ page_cache_readahead_adaptive(struct add end_index - index); return 0; } + if (laptop_mode && laptop_spinned_down()) { + if (!renew_lookahead(mapping, ra, index, + index + LAPTOP_POLL_INTERVAL)) + return 0; + } } if (page) -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/